Bulging apparatus

ABSTRACT

A fluid pressure bulging apparatus for bulging tubular work is connected with a pressure generating means. A dummy block is fitted to one end of the tube being worked in order to automatically move the work axially by the hydraulic fluid pressure which is exerted on the inside of the work.

United States Patent Nakamura 1451 Aug. 22, 1972 1 BULGING APPARATUS[72] Inventor: Masanobu Nakamura, 2-10-2,

Shichirigahama, I-ligashi, Kamakura,Japan 22 Filed: Nov. 12, 1969 [21Appl. No.: 875,967

3,494,160 2/ i 970 Tominaga et al. ..72/60 3,105,537- 10/1963 Foster..72/370 FOREIGN PATENTS OR APPLICATIONS 24,746 10/ 1969 Japan ..76/56Primary Examiner-Richard J. Herbst Attorney-Jacobi, Lilling & Siege][57] ABSTRACT A fluid pressure bulging apparatus for bulging tubularwork is connected with a pressure generating means. A dummy block isfitted to one end of the tube being worked in order to automaticallymove the work axially by the hydraulic fluid pressure which is exertedon the inside of the work.

1 Claim, 2 Drawing figures PATENTED M1822 m2 5 on B 6 mm 3 mm 3 mm E mmmm 0w 5 mm INYENTOR Maia/a8 ///7Ki/W 4 R A j/aww' Aim 50% ATTORNEYSBULGING APPARATUS This invention relates to a bulging apparatus forbulging part of pipe to a desired contour with pressure exerted byhydraulic means on fluid filled in the blank.

It is a principal object of the present invention to provide a bulgingapparatus wherein only one ends of dies are connected to a pistonchamber of hydraulic pres sure generating means and the piston in saidchamber is actuated to apply a pressure to the hydraulic fluid filled ina length of pipe placed in the cavity of the dies so that the bulgingcan be accomplished without the need of any external piping.

Another object of the invention is to provide a bulging apparatuswherein a dummy block fitted to one end of pipe being worked isautomatically moved axially by hydraulic fluid as pressure is exerted onthe fluid inside the pipe in the manner above described, so as tosupport the pipe end firmly and securely and permit the bulging to beperformed in a reliable way.

Another object is to provide a bulging apparatus wherein air inside thepipe to be worked is automatically bled off as the pipe is filled withhydraulic fluid.

Still another object is to provide a bulging apparatus wherein a supportpad fitted to the front end of the pipe is moved axially and pulled offfrom the pipe with ease on completion of a bulging operation, so thatthe bulged pipe can be readily removed from the die cavity.

These and other objects of the present invention should become apparentfrom the following detailed description taken in conjunction with theaccompanying drawings showing embodiments thereof.

In the drawings:

FIG. 1 is a longitudinal sectional view of an embodiment of theinvention; and

FIG. 2 is a similar longitudinal sectional view of another embodiment ofthe invention.

In FIG. 1 there is shown a longitudinal section a bulging apparatusembodying the invention wherein application of a pressure to thehydraulic fluid causes a pipe to be worked inside to be pressed at therear end in the axial direction.

In the figure, reference numeral 1 generally indicates dies of splittype comprised of an upper die 2 and a lower die 3, each formed with arecess axially on the surface opposite to each other, thus defining acavity 4 to receive a length of pipe 5 as a work to be bulged.

The cavity 4 is communicated at the rear end, or at the left end asviewed in the figure, with a piston chamber 6 of a hydraulic pressuregenerator 7 via a tapered passage 8, in such a manner that, when thecavity 4, passage 8, and piston chamber 6 are filled with hydraulicfluid and a piston 9 provided through the top wall of the piston chamberis suitably moved downward to exert a pressure on the fluid inside thechamber, the pressure is transmitted through the passage 8 into thecavity 4.

Inside the cavity 4 there is suitably held a bleed pipe 10 fordischarging air out of the blank 5 as the latter is filled with thehydraulic fluid. The bleed pipe 10 is bent slightly upward at the frontend 1 1, and is open near the inner wall surface of the pipe portion tobe bulged. The bleed pipe 10 is provided with a valve 12 at a suitablepoint.

At the entrace of the cavity 4 is provided a pressure member or dummyblock 13 which in response to the pressure of the hydraulic fluidautomatically presses the base end or the left end of the pipe 5 forwardto secure a grip of the pipe for working.

The dummy block 13 is a cylinder having a through hole in the center andis slidably inserted in the left-end entrance of the cavity 4, whilemaintaining liquidtightness as with an O-ring 14. At its lower endportion the block 13 is stepped to form a reduced-diameter portion 15,which just fits in the mating end of the pipe 5. Thus, the area of theleft end face 16 of the dummy block which is subjected to the hydraulicpressure is somewhat larger than the pressure-receiving area of theright end face 17.

Accordingly, if the piston 9 of the hydraulic pressure generator 7 isactuated downward to exert a pressure on the hydraulic fluid in thefluid passage 8 and also in the pipe 5 inside the cavity 4 of the dies1, the left end fact 16 of the dummy block 13 is subjected to a greaterfluid pressure than is the right end face 17 with the result that thepressure differential causes the reduced diameter portion 15 of thedummy block 13 to be fitted securely into the left end portion of thepipe 5 and thereby press the left end of the pipe 5.

The base or rear end portion of the upper die 2 of the dies 1 ispivotally connected to the hydraulic pressure generator 7 withhorizontal pivot or pin 18 in such a way that the upper die can turn uparound the pivot to open or close the dies.

The frontal exterior of the dies 1 is tapered over a desired length, sothat a clamping cylinder or sheath 19 having a matching tapered innerwall can be moved toward the hydraulic pressure generator 7 by suitablemeans thereby to clamp the upper die 2 and the lower die 3 firmlytogether.

Inside a hole 20 formed in the frontal ends of the dies 1 there isinserted, slidably with an O-ring 21, a support pad 22 which is fittedin the right end portion of the pipe 5 to provide a support to the pipe.A threaded portion 23 at the outer end of the support pad 22 is screwedin a nut 24 which fits in an internally threaded hole 25 formedoutwardly of the hole 20, so that the support pad 22 can be movedaxially as desired by tuming the nut 24.

In the embodiment shown, numeral 26 indicates an outer sleeve forsupporting the dummy block 13; 27 indicates an O-ring; 28 indicates ahydraulic fluid line to the piston chamber 6; and 29 indicates a valveprovided at a suitable point of the line. 30 is a small passageway whichcommunicates the cavity of the dies with the surrounding atmosphereduring the bulging process of the pipe.

The operation of the apparatus according to the present invention willnow be explained. First, the nut 24 is turned and the support pad 22 isurged a desired distance into the front end portion of the cavity 4. Alength of pipe 5 to be bulged is placed in the cavity 4, with the rightend portion being fitted in and supported by an annular space 31 definedbetween the cavity 4 and the support pad 22, and then both of the valves12 and 29 are opened so that hydraulic fluid may be introduced into thepipe 5 by way of the piston chamber the bleed pipe 10, the both valves12, 29 are closed and the fluid is no longer introduced into theapparatus.

Next, the piston 9 of the hydraulic pressure generator 7 is forceddownward suitably as by a press to exert a pressure on the fluid insidethe piston chamber 6, and the pressure is conducted to the fluid insidethe pipe thereby to cause bulging of the pipe 5, as desired, to theconfiguration of the cavity 4 defined by the dies 1.

In the apparatus of the invention, as already stated, the application ofa pressure to the hydraulic fluid inside the pipe 5 produces a pressuredifferential based on the difference between the pressure-receivingareas of the inner and outer end faces 16, 17 of the dummy block 13fitted in the entrance of the cavity 4 of the dies, which in turnnaturally urges the dummy block 13 deep into the cavity 4, until theleft end of the pipe is fitted in a space 32 defined between the rightend of the dummy block 13 and the cavity 4 and, at the same time, thestepped portion representing a shoulder for the reduced-diameter portion15 of the dummy block 13 pressed the left end portion of the pipe 5unmovably.

Thus, with the construction according to the invention, the both ends ofthe pipe 5 to be bulged are gripped at both the exterior and interiorsurfaces over desired distances by combinations of the support pad 22and the cavity 5 and also of the reduced-diameter portion 15 of thedummy block 13 and the cavity 4, and are supported with a pressureaxially exerted on the both ends of the pipe 5. This enables the pipe 5during subsequent working to be accurately bulged without any deviationfrom the axis. The arrangement also precludes the possibility ofundesirable information of the pipe ends due to subjection to anyexcessive force.

Further, in the apparatus of the invention, the withdrawal of the bulgedpipe from the cavity 4 can be accomplished with extreme ease to anadvantage because, even if the pipe 5 being worked may be too tightlyfastened by the dummy block 13 or the support pad 22, the pipe can bereadily liberated by turning the nut 24 and pulling off the support pad22 from the pipe 5.

FIG. 2 shows, in a longitudinal section, another embodiment of thebulging apparatus of the invention, wherein hydraulic fluid exertspressure axially on the pipe not only to the rear end but also to thefront end thereof.

As shown, dies generally indicated at 41 are of split type, consistingof upper and lower dies, having recesses on the opposing faces to definea longitudinal cavity 42 large enough to receive a length of pipe 43 tobe bulged. The rear end portion (or the left end portion as viewed inthe figure) of the cavity 42is communicated to a hydraulic pressuregenerator 44 via a communicating hole or passage 45, while the front end(or the right end) portion faces a chamber 46 contiguous thereto butwhich is expanded and has a larger diameter than that of the die cavity.

The expanded chamber 46 is defined by inserting a cylindrical body 47having an end wall 48 at the front end thereof, into the large-diameterhole 49 formed at the front end of the dies 41, so that the space insidethe cylindrical body 47 can serve as the expanded chamber 46.

Through a center hole of the front end wall 48 of the cylindrical body47 there is inserted a stopper 50 slidably and in liquid-tight manner.The stopper is formed suitably with a neck-line small-diameter portion51 and a medium-diameter portion 52 in one piece, the portion 52 beingsmaller in diameter than the inside diameter of the pipe 43 to beworked. A hole 53 is formed through the stopper 50, from the inner endface of the medium-diameter portion 52 to the outer end face of thestopper 50.

The intermediate portion 51 of the stopper 50 is fitted in a hole 54 ofa cylindrical chuck 55, an O-ring 56 establishing a liquid-tight sealtherebetween. The outer surface of the chuck is adapted to slide alongthe inner wall surface of the expandedchamber 46 while maintainingliquid-tightness by means of an O- ring 57.

The through hole 53 of the stopper s0 is opened in an enclosed chamber58 defined between the outer end face of the chuck 55 and the inner endface of the front end wall 48 of the cylindrical body 47.

In continuation of the inner end of the hole 54 of the chuck 55, thereis formed integrally a tapered hole59 which is slightly increased indiameter at the inner end so that the outeredge of the front end portionof the pipe 43 to be worked can tightly fit therein.

At the rear end of the dies 41, a cylindrical presser or dummy block 60is inserted in the cavity 42 so as to exert a pressure on the rear edgeof the pipe 43 placed inside the cavity 42.

The dummy block 60 is formed at the front end with a stepped,small-diameter portion adapted to fit in the rear end portion of thepipe 43, the small-diameter portion being such that when it is fittedin-the pipe 43 the area at the front'end of the dummy'block 60 which issubjected to the pressure of the hydraulic fluid is smaller than that ofthe rear end, so that upon application of a pressure to the hydraulicfluid the block 60 is urged frontwardly the pressure differential due tothe different pressure is exerted on the rear end portion of the pipe43.

The rear end portion of the upper die of the dies 41 is pivotallyconnected with a pivot 61 to the front end portion of a connectingcylinder 62 adjacent the hydraulic pressure generator 44. Thus upper dieis movable upward around the pivot 61 to open the dies by suitablehydraulic means not shown.

The exterior of the dies 41 over a desired length from the front end(right end) is tapered, the front end being the smallest in diameter.From the front end of this tapered exterior rearward, a clampingcylinder or sheath 63 having a matching tapered hole 64 is fitted, thusfastening the upper and lower dies tightly together.

After the blank pipe 43 has been bulged, the stopper 50 is caused toslide outwardly by suitable external force. Then, the inner end portion52 of the stopper 50, which fits in to a shoulder portion 65 of thechuck 55, forces the chuck away from the pipe 43.

The rear end portion of a small-diameter air vent pipe 66 providedthrough the dummy block 60 extends rearwardly through the communicatingpassage 45 and the hydraulic pressure generator 44 to an external valve67 for communication with On the other hand, the front end portion 68 ofthe vent pipe 66 is bent upwardly substantially in the middle portion ofthe cavity 42 so that it is open close to the inner wall surface of thepipe 43 to be worked.

In the embodiment shown, reference numeral 69 designates a reservoir forhydraulic fluid in the hydraulic pressure generator 44. A piston 70exerts a pressure on the hydraulic fluid in the reservoir 69 and henceto the fluid in the pipe 43 held inside the cavity 42 of the dies 41 viathe passage 45. The cavity 42 is formed with a spherical recess 71 at asuitable point for bulging purpose. Numeral 72 indicates a line forsupplying hydraulic fluid to the reservoir 69, and numeral 73 indicatesa valve provided midway the line 72. 74 is a small passagewaycommunicating the recess 71 of cavity 42 with the surroundingatmosphere.

The apparatus of the foregoing construction according to the presentinvention is operated as follows. A length of pipe 43 to be bulged isplaced in the cavity 42 of the dies 41, and the front end (right end)portion of the pipe 43 is fitted in the tapered hole 59 of the chuck 55inside the expanded chamber 46 and, at the same time, the rear end (leftend) portion of the pipe 43 is received with the dummy block 60, and thevalves 67 and 73 are opened so that hydraulic fluid may be introducedinto the reservoir 69, passage 45, and pipe 43.

Then, asthe fluid enters the pipe 43, the air inside the pipe 43 isdriven out through the air vent pipe 66. When the bleeding has beencompleted, or when the fluid has begun overflowing from the outer end ofthe vent pipe 66, the valves 67 and 73 are both closed.

Next, the piston 70 of the hydraulic pressure generator 44 is forceddownward suitably as by a press to exert a pressure on the fluid in thereservoir 69 and the fluid pressure in turn is transmitted to the fluidinside the pipe 43, so that the pipe 43 is bulged as desired to thecontour of the cavity 42.

The front end portion of the pipe 43, which is fitted in the taperedhole 59 of the chuck 55, is urged into closer engagement with the latterupon the application of the pressure to the hydraulic fluid in the pipe43, whereby the front end portion of the pipe 43 is rigidly and securelygripped and held under pressure.

As hydraulic fluid is forced into the pipe 43, part of the fluid flowsthrough the hole 53 of the stopper 50 into the enclosed chamber 58between the outer end face of the chuck S5 and the front end wall 48,thereby to urge the chuck 61 backward.

Since the stopper 50 is slidable with respect to the front end wall 48of the cylindrical body 47, the chuck 55 is urged out, together with thestopper 50, toward the pipe 43, with the result that the tapered hole 59gets in closer engagement with the front end portion of the pipe 43.

Accordingly, the front end portion of the pipe 43 is tightly gripped bythe tapered hole 59 of the chuck 55 and is held under pressure by theengagement with the shoulder 65 of the chuck 55. This makes it possibleto perform bulging of the pipe 43 accurately without any possibility ofpositional deviation or vibration.

After the bulging of the pipe 43, the chuck 55 is suitably slid out toleave the front end portion of the pipe 43 away therefrom, and thesheath 63 is slid off outwardly from the dies 41. Then, the upper die ofthe dies 41 is turned upwardly around the pivot 61 to open the dies andremove the bulged pipe 43 readily and simply from the cavity 42 to agreat advantage.

What is claimed is. l. A bulging apparatus of the type employed to shapea pipe by means of hydraulic fluid under pressure, said apparatuscomprising: cavity means having a cavity therein for receiving the pipeand having an enlarged front end and a rear end, said rear end of saidcavity closely conformed to the external cylindrical dimensions of thepipe; retaining means, for retaining the pipe at said front end of saidcavity, comprising a chuck within said enlarged said front end portionand in sealing engagement with the walls of said cavity such that aportion of said enlarged portion is in front of said chuck and separatedthereby from the remainder of said cavity, said chuck is adapted tograsp the pipe such that as the fluid pressure is increased the pipe isforced into greater engagement with said chuck, said chuck having anaperture extending axially therethrough, a stopper extends within saidchuck through said chuck aperture, said stopper having an aperturetherein for passing the hydraulic fluid from said cavity to saidenlarged portion of said cavity in front of said chuck such that as thehydraulic pressure is exerted said chuck is thereby forced rearwardlyagainst the pipe; hydraulic means for providing the hydraulic fluidunder pressure to said cavity; dummy block means secured at said rearend of said cavity and in sealing engagement therewith and having afront portion thereof extending into said cavity for engaging pipe andan aperture extending from a rear portion through to a front portionthereof so as to admit the hydraulic fluid into said cavity, said frontportion having a smaller cross-sectional area than said rear portionsuch that upon the hydraulic fluid being supplied to said cavity theresultant pressure upon said rear portion causes said dummy block tomove toward said front end of said cavity; said cavity has at least onebulging configuration therein, a bleed pipe extending within said cavityand without through said aperture of said dummy block, and said bleedpipe curving upwardly within said cavity proximate said bulgingconfiguration.

1. A bulging apparatus of the type employed to shape a pipe by means of hydraulic fluid under pressure, said apparatus comprising: cavity means having a cavity therein for receiving the pipe and having an enlarged front end and a rear end, said rear end of said cavity closely conformed to the external cylindrical dimensions of the pipe; retaining means, for retaining the pipe at said front end of said cavity, comprising a chuck within said enlarged said front end portion and in sealing engagement with the walls of said cavity such that a portion of said enlarged portion is in front of said chuck and separated thereby from the remainder of said cavity, said chuck is adapted to grasp the pipe such that as the fluid pressure is increased the pipe is forced into greater engagement with said chuck, said chuck having an aperture extending axially therethrough, a stopper extends within said chuck through said chuck aperture, said stopper having an aperture therein for passing the hydraulic fluid from said cavity to said enlarged portion of said cavity in front of said chuck such that as the hydraulic pressure is exerted said chuck is thereby forced rearwardly against the pipe; hydraulic means for providing the hydraulic fluid under pressure to said cavity; dummy block means secured at said rear end of said cavity and in sealing engagement therewith and having a front portion thereof extending into said cavity for engaging pipe and an aperture extending from a rear portion through to a front portion thereof so as to admit the hydraulic fluid into said cavity, said front portion having a smaller cross-sectional area than said rear portion such that upon the hydraulic fluid being supplied to said cavity the resultant pressure upon said rear portion causes said dummy block to move toward said front end of said cavity; said cavity has at least one bulging configuration therein, a bleed pipe extending within said cavity and without through said aperture of said dummy block, and said bleed pipe curving upwardly within said cavity proximate said bulging configuration. 